A method and device of this kind are known from the Handbook, "Practical NMR Imaging", M. A. Foster and J. M. S. Hutchinson, 1987, IRL Press, pp. 15-22, and pp. 28-38. A Fourier transform sequence is given at page 19 and a blockdiagram of an NMR imaging device is shown at page 29 of the Handbook. In the method the body is irradiated with an rf-pulse, e.g. a 90.degree. pulse, in the presence of a slice selection gradient, thus flipping atomic spins, such as nuclear spins or with adaptations electron spins, of a slice of the body in a rotating frame rotating with the Larmor frequency by an angle of 90.degree., resulting in an FID-signal (free induction decay). Then the FID-signal is succesively dephased by a reading gradient having a first polarity and rephased by reversing the reading gradient. During rephasing a so called gradient recalled echo occurs. Two dimensional coding is achieved by applying a variable amplitude phase encoding gradient and by sampling the echo signal. Fourier reconstruction gives a spatially resolved spin distribution of the slice that can be displayed on a monitor as a grey scale image e.g. Extension to 3D-imaging is well known and straight forward so is a modification of the sequence to a so called projection reconstruction sequence. In the sequence the maximum of the echo occurs at a point of time t.sub.e from the center of the pulse at t.sub.o. The time difference t.sub.e -t.sub.o is the so called echo time, which may not be chosen too small in case a complete echo is to be sampled. A too small echo time causes echo distortion and eventually image artefacts. In case short echo times are desired, e.g. for Sodium-imaging, for less flow artefacts, or for obtaining a different image contrast, a distorted echo could only be sampled to the echo maximum or so (asymmetric sampling). Ideally the image would be real, and displaying the real part of the image would suffice. But due to inter alia B.sub.O -inhomogeneities, susceptibility, eddy currents and flow, the image is not real. Thus, direct real-part reconstruction or, equivalently, data mirroring in k-space often leads to unacceptable image artefacts. Correction methods are known for correcting some of these problems e.g. from the European Patent Application No. 0 250 050, which corresponds to U.S. Pat. No. 4,853,635, giving an iterative correction algorithm. This algorithm needs more than half of the k-space (e.g. 5/8-th of an echo is sampled), thus restricting echo time reduction. Such correction methods tend to be artefact-sensitive if 50% of the data in k-space is missing, or if the phase varies rapidly over the image in the case of blood flow e.g. Then it would be expedient to acquire data over the whole k-space.